Fire alarm



May 2, 1939- T. LUsAR'z 2,156,437

FIRE ALARM Filed Jan. 14, 1957 29 T70 Mens Patented May 2, 1939 UNITEDSTATES FIRE ALARM Tadeusz Slusarz, Warsaw, Poland Application January14, 1937, Serial No. 120,463 In Germany November 19, 1936 'Z Claims.

Fires frequently assume great dimensions because the re is noticed toolate. 'Ihe fire is often only noticed after it has made its Way to theoutside of the building. 'Ihis is in particular the case With factoriesand warehouses, museums and similar buildings in which work ceasesduring the night.

Fire alarm devices are already known which are caused to operate bymeans Aoi the fusing or expansion of an indicating substance takingplace with a sudden rise of temperature. These devices are, however,objectionable since they frequently give an indication only when inconsequence of the iire the temperature has risen by several degrees.

The present invention relates to a device which indicates the outbreakof a fire even if the temperature of the room in which the device issituated. has risen under the influence of the ire by only a fewdegrees, and this independently oi the temperature prevailing in thesaid room before the fire started.

According to the present invention any desired alarm device is actuatedby means of a small freely suspended container which in consequence ofthe alteration in the density of the surrounding air, caused by thefire, sinks and thereby switches in or out the alarm device.

The weight of the air, as is known, is reduced in inverse ratio to thetemperature of the air and the air in a confined space, e. g., in aroom, will be heated under the direct influence of the flames morequickly than under the eiiect of climatic changes or central or stoveheating. This fact is utilized in the construction of the deviceaccording to the present invention, the walls of the container beinggiven such a degree of heat conductivity that the device only respondsto fire but not to a gradual rise of temperature.

In the accompanying drawing is shown a construction of the deviceaccording to the present invention, by Way of example:

Figure 1 is an elevation of the device; Figure 2 is a vertical sectionthrough the device according to Figure l; and Figure 3 is a horizontalsection through the device on the line A-B of Figure 2.

The device according to the present invention comprises a casing I,which contains three chambers a, Zi, c. In the central chamber b ismounted the balance frame 2 with the balance beam 3. On one end of thebalance beam is suspended in the chamber c a small container 4 and atthe other end of the balance beam there is suspended a counterweight 5.The device is provided with one single container 4, while thecounterweight 5 consists of a piece of sheet metal having surfaces equalin area to the outer surfaces of the container 4, so that the Weight ofthe dust settling on the container 4 will be equal to the weight of 5the dust settling on the counterweight 5. The counterweight 5 ispreferably corrugated and has the form of an open cylinder having nobottom. One pole V of the source of current is connected to the casingI, whilst the other pole V is insu- 10 lated from it and is introducedinto the interior of the casing. The balance beam consequently on theincrease of the weight of the container touches the pole V', closes thecurrent circuit and thus switches on the alarm device (not shown). 1n 15the wall of the chamber b there is inserted in the current circuit achecking incandescent lamp 5.

The balance beam 3 is in its usual position slightly overloaded on theside of the counter- 20 weight in such manner that it rests by means ofthe spring 8 on the pin 'I. This spring prevents any bouncing of thebalance beam from the supports in the case of the apparatus beingshaken, so that no false alarm is caused thereby. 25

The casing I is provided with lugs 3 intended to fasten the device onthe wall, and also with a plumb bob I0.

In order to ensure the operativeness of the device, its essential parts,namely the container, 30 the balance beam and the counterweight, must bemost carefully protected from injury which might be caused by dust,insects, draught and the like. For this reason, the device is providedwith an envelope II which is situated within the 30 easing l and aroundthe container 4 and which permits the inow of the heat to the interiorof the chamber c but at the same time to a large extent protects theseconstituents of the device from external influences. The envelope il is40 either made from a very dense fabric or from a very thin metal plateof great heat conductivity. The envelope II enclcses the chamber c inwhich the container 4 is situated. The openings i2 45 or the casing iare covered by caps I2. As the casing I cannot be closed air-tightly, itdoes not protect the small container 4 completely from the penetrationof small particles of dust, so that it Wouid be possible for thecontainer at the 50 expiration of a certain time and under the influenceof this load, to fall and effect an unnecessary alarm. To prevent this,the counterweight is made of the same material as the container 4 andhas a similar surface to the container, so that the 55 amount of thedust settling on both sides of the balance beam must always be the same.

Since, under the influence of the varying barometrical pressure, thedensity of the air and vwith it also the weight of the air in the roomundergo variations whilst the weight of the air enclosed in thecontainer 4 always remains the same, this might lead to an undesireddeection of the balance in one direction or the other, and thus to anunnecessary alarm. To prevent this, the container 4 has an opening I3provided with a cover is which permits outside air to penetrategradually into the interior of the container fl, so that in case of achange in atmospheric pressure around the container 4 a gradualequalisation of the density of air on the outside and inside of thecontainer 4 can take place. However, the cover I3 prevents dust fromreaching the interior of the container 4. The cover i3' may be made of adense fabric or the like.

The device operates in the following way:

At the outbreak of a iire, there is a sudden rise in the temperature ofthe air in the room in which the alarm device is situated. The warmedair passes through the openings l2 of the casing i through the envelopel! into the interior or" the chamber c which results, in a rapid heatingoi the air in the chamber c, if the envelope li is made of a thin metalplate of good heat conductivity. The decrease thereby caused in thedensity of the air surrounding the container l causes the sinking orthis latter, whereby the balance beam 3 comes into contact with thecontact piece V and switches in the alarm device.

Since the counterweight 5 is open at the bottom, no separate means tocompensate for ambient temperature changes are required for thecompartment a. The clearance in the compartment b is not suiicient tohave a balancing effect of the ambient air in the compartments a and c.

Having now particularly described and ascertained the nature of my saidinvention and in what manner the same is to be performed, declare thatwhat I claim is:

l. ln a fire alarm having a normally balanced beam, a hollow containerfilled with air suspended from one end oi said beam and having wallswhich ar rapid and excellent conductors of heat, incluis connected'withsaid beam for balancing the same, and means connected with said beam forlosing an electrical circuit when said beam is thrown out oi" balancedue to a change in the buoyancy of said container resulting from anabnormally quick rise in temperature of the air surrounding saidcontainer.

2. In a fire alarm havingr a normally balanced beam, a hollow containerfilled with air suspended from one end of said beam and having wallswhich rapid and excellent conductors of heat, means connected with saidbeam for balancing the same, means connected with said beam for closingan electrical circuit when said beam is thrown out or" balance due to achange in the buoyancy of said container resulting from an abnormallyquick rise in temperature of the air surrounding said container, acasing surrounding said container and having openings formed therein,and caps covering said openings.

3. In a nre alarm having a normally balanced beam, a hollow containersuspended from one end ci said beam and having walls which are rapid andexcellent conductors of heat, means connected with said beam forbalancing the same,

means connected with said beam for closing an electrical circuit whensaid beam is thrown out of balance due to a change in the buoyancy ofsaid container resulting from an abnormally quick rise in temperature ofthe air surrounding said container, a casing surrounding said containerand having openings formed therein, and an envelope consisting of adense fabric and situated within said casing, said envelope surroundingsaid container.

4. In a fire alarm having a normally balanced beam, a hollow containersuspended from one end oi said beam and having walls which are rapid andexcellent conductors of heat, means connected with said beam forbalancing the same, means connected with said beam for closing anelectrical circuit when said beam is thrown out o balance due to achange in the buoyancy of said container resulting from an abnormallyquick rise in temperature of the air surrounding said container', acasing surrounding said container and having openings formed therein,and an envelope consisting of a thin metallic plate of high heatconductivity, said envelope being situated within said casing andsurrounding said container.

5. in a ro alarm having a normally balanced beam, a hollow containersuspended from one end of said beam and having walls which are rapid andexcellent conductors of heat, a corrugated eounterweight suspended fromthe other end of beam to balance the same, the area of the surfaces oisaid counterweignt being equal to 1 of the surfaces of said container,and means co-.nected with said beam for closing an elec- .al circuitwhen said beam is thrown out of tion of air in the interior of saidcontainer with the air surrounding said container upon variation oibaroinetric pressure, means connected with said beam for balancing thesame, and means connected with said beam for closing an electricalcircuit when said beam is thrown out of balance due to a change in thebuoyancy of said container resulting from an abnormally quick rise intemperature of the air surrounding said container.

7. in a nre alarm having a beam, a hollow container suspended from oneend of said beam and having walls which are rapid and excellentconductors ci heat, a counterweight suspended from the other end of saidbeam and being somewhat heavier than said container, whereby said beamis noirnally somewhat overloaded on the side of said ccunterweight, aspring carried by said beam, a pin engaged by said spring in theoverloaded position of said beam, whereby said beam is resting said pinin said overloaded position, and means connected with said beam forclosing an electrical circuit when said beam is moved out of saidoverloaded position due to a change in the buoyancy of said containerresulting from an abnormally quick rise in temperature of the airsurrounding said container.

